Another 20 g of alkali was dissolved in 180 g of a 15% sodium hydroxide solution

univerkov | June 20, 2021 | education

Another 20 g of alkali was dissolved in 180 g of a 15% sodium hydroxide solution, calculate the mass fraction of alkali in the resulting solution

The mass of sodium hydroxide in the original solution.
m (NaOH) = W (NaOH) • m (solution) / 100% = 15% • 180 g / 100% = 27 g.
The mass of alkali in the resulting solution.
m (NaOH) = 27 g + 20 g = 47 g.
The mass of the solution after adding sodium hydroxide.
m (solution) = 180 g + 47 g = 227 g.
Mass fraction of hydroxide in solution.
W (NaOH) = m (NaOH) / m (solution) • 100% = 47 g / 227 g • 100% = 20.7%.

One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.